1. Technical Field
The present invention generally relates to a method for predicting catalyst performance in catalyst processes in the refining and petrochemical industry.
2. Description of the Related Art
Hydroprocessing, which includes by way of example hydroconversion, hydrocracking, hydrotreating, hydrogenation, hydrofinishing and hydroisomerization, plays an important role in upgrading petroleum feedstocks to meet the more stringent quality requirements. For example, there is an increasing demand for improved hetero-atom removal, aromatic saturation, and boiling point reduction as well as removal of metal contaminants such as vanadium and nickel. Much work is presently being done in hydrotreating because of greater demands for the removal of undesirable components such as heteroatoms, most notably sulfur, from transportation and heating fuel streams. Hydrotreating is well known in the art and usually involves treating the petroleum streams with hydrogen in the presence of a supported catalyst at hydrotreating conditions.
Hydrocarbon feedstocks likewise generally contain polar core materials, i.e., polyaromatics such as asphaltenes, dispersed in lower polarity solvent(s). Intermediate polarity material(s), usually referred to as resin(s), can associate with the polar core materials to maintain a homogeneous mixture of the components.
Asphaltenes are organic heterocyclic macromolecules which occur in crude oils. Under normal reservoir conditions, asphaltenes are usually stabilized in the crude oil by maltenes and resins that are chemically compatible with asphaltenes, but that have lower molecular weight. Polar regions of the maltenes and resins surround the asphaltene while non-polar regions are attracted to the oil phase. However, changes in pressure, temperature or concentration of the crude oil can alter the stability of the dispersion and increase the tendency of the asphaltenes to agglomerate into larger particles. As these asphaltene agglomerates grow, so does their tendency to precipitate out of solution.
One of the problems encountered in crude oil production and refining is coking. Processes that utilize catalysts to process a hydrocarbon-containing material containing one or more polyaromatic compound suffer significantly from catalyst aging due to coke deposition on the catalyst over time. In general, as the one or more polyaromatic compound precipitate out of the hydrocarbon-containing feed during hydroprocessing, the precipitated polyaromatic(s) deposit onto the catalyst and form coke. As the coke that is formed on the catalyst progresses over time, plugging of the catalyst pores and covering of the surface of the catalyst occurs. In time, the coked catalyst loses its catalytic activity and, ultimately, must be replaced.
Accordingly, it would be advantageous to predict catalyst performance in the refining and petrochemical industry in a method that can be carried out in a simple, cost efficient and repeatable manner.